Cancer risk assessment of 1,3-butadiene.

Abstract

This paper discusses the Environmental Protection Agency's (EPA) risk assessment of 1,3-butadiene. The assessment focuses on estimation of increased cancer risk to populations living near industrial sources of 1,3-butadiene emissions rather than occupationally exposed populations. Incremental cancer risk estimates based on extrapolation from laboratory animal data are presented. Pharmacokinetic data published since the EPA's 1985 assessment are incorporated, which somewhat alters the earlier assessment of cancer risk. Characterization of emission sources, estimates of ambient air concentrations, and population exposure are also discussed. The estimate presented in this paper of excess cancer cases resulting from point source exposure to 1,3-butadiene is decreased to approximately 40% of the estimate published in 1985 from 6.4 in 10 to 2.5 chances in 10 for a lifetime exposure to 1 ppm. The current estimate is no more than eight additional cancer incidences in the general population. Increased risk to the most exposed individuals is not anticipated to be greater than 1 in 10. This reduction in the risk estimate is due to a change in the estimate of 1,3-butadiene potency (i.e., incremental unit risk estimate) based on incorporation of new pharmacokinetic data.

Experimental and Ab Initio Dynamical Investigations of the Kinetics and Intramolecular Energy Transfer Mechanisms for the OH + 1,3-Butadiene Reaction between 263 and 423 K at Low Pressure

“…From Figure 12, we also note that there is longer time scale (8-18 ps) exchange between the ν 1 and ν 5 modes. Figure 12 further depicts exchange between the CO stretch mode (described by ν 13 in Figure 12a and c) and an umbrella motion of the attached H atoms. It is already indicative that the hydrogen bonded to the C2 atom of butadiene participates, albeit weakly, in energy transfer through its interaction with the OH oxygen.…”

Comparison of breath, blood and urine concentrations in the biomonitoring of environmental exposure to 1,3-butadiene, 2,5-dimethylfuran, and benzene

“…Sources of both substances are automobile exhaust fumes, domestic fires and tobacco combustion (Neligan 1962). Butadiene accounts for roughly 0.35% of total hydrocarbons in exhaust emissions, in which it may reach concentrations of as much as 20-60 ppb (44-132 lg/m 3 ) (Cote and Bayard 1990). In smoke from domestic fires, it has been detected at levels as high as 15 ppm (33 mg/m 3 ) (Berg et al 1978).…”

Residential environmental measurements in the National Human Exposure Assessment Survey (NHEXAS) pilot study in Arizona: preliminary results for pesticides and VOCs

“…Vehicle emissions are a major outdoor source of this pollutant (Lofgren and Petersson, 1992), and vehicle exhaust and evaporative emissions of fuel from vehicles may enter the living space of houses with attached garages (Hodgson and Wooley, 1991). Low levels of 1,3-butadiene have been measured in ambient urban air (Cote and Bayard, 1990;Lofgren and Petersson, 1992). Although it is a probable human carcinogen (Hallenbeck, 1992), data on indoor levels of 1,3-butadiene are sparse (Sheldon et al, 1992).…”